Emergent particle-hole symmetry in spinful bosonic quantum Hall systems

Abstract

When a fermionic quantum Hall system is projected into the lowest Landau level, there is an exact particle-hole symmetry between filling fractions $ν$ and $1-ν$. We investigate whether a similar symmetry can emerge in bosonic quantum Hall states, where it would connect states at filling fractions $ν$ and $2-ν$. We begin by showing that the particle-hole conjugate to a composite fermion `Jain state' is another Jain state, obtained by reverse flux attachment. We show how information such as the shift and the edge theory can be obtained for states which are particle-hole conjugates. Using the techniques of exact diagonalization and infinite density matrix renormalization group, we study a system of two-component (i.e., spinful) bosons, interacting via a $δ$-function potential. We first obtain real-space entanglement spectra for the bosonic integer quantum Hall effect at $ν=2$, which plays the role of a filled Landau level for the bosonic system. We then show that at $ν=4/3$ the system is described by a Jain state which is the particle-hole conjugate of the Halperin (221) state at $ν=2/3$. We show a similar relationship between non-singlet states at $ν=1/2$ and $ν=3/2$. We also study the case of $ν=1$, providing unambiguous evidence that the ground state is a composite Fermi liquid. Taken together our results demonstrate that there is indeed an emergent particle-hole symmetry in bosonic quantum Hall systems.